Genetics: My herd is comprised of percentage Kiko does bred to a purebred Kiko buck. Once I have bred them up to full blood Kiko's I will start using a Boer buck on all terminal does, as well as some that are not terminal, so I have the benefit of mitochondrial DNA.
Profit: Yes, technically I am making a profit. My situation is a little different than most people, though. I work on the family farm, and we raise hay. I do not have to pay for my hay because I bust my butt all summer long irrigating, keeping noxious weeds out of it, controlling the gophers, etc., but I still include it in my costs. Until the drought hit and hay prices went through the roof I was making a profit. If I had enough pasture for 5 to 6 months of grazing a year I would still be making a profit even with the current price of hay.
I do not keep replacement bucks - I buy them. The reason for that is because of fresh bloodlines. Any buck I raise is related to at least his mother, and a good number of my does are twins and have doelings in the herd. I do not believe in line breeding. My #1 criteria for replacement does is mothering. When you get right down to it, if a doe is not a good mother the rest doesn't matter. Any doe that rejects kids without a damned good reason is on the next trailer out of here. I will NOT tolerate it. There are too many good does out there to put up with one that won't accept her kids. 2nd is conformation, udder structure, and milking ability.
Ups and Downs: I'm not exactly sure what you are looking for with this question. What may be a down for me won't be for you because of the difference in where we live and other things.